Steam generator having an integrated modular heat exchanger

ABSTRACT

A modular heat exchanger assembly for a steam generator includes a first fluid inlet conduit configured and disposed to be connected to a source of a first fluid, and a tube sheet coupled to the first fluid inlet conduit. The tube sheet includes a first surface and an opposing, second surface. A plurality of platen tubes extends from the second surface of the tube sheet. The plurality of platen tubes is configured and disposed to carry a second fluid in a heat exchange relationship with the first fluid in a heat exchange vessel. The modular heat exchanger assembly is configured and disposed to be selectively and readily removable from the heat exchange vessel.

BACKGROUND OF THE DISCLOSURE

The subject matter disclosed herein relates to the art of steam generators and, more particularly, to a steam generator having an integrated modular heat exchanger.

Steam generators extract heat from one fluid into a second fluid to produce steam. Typically, the second fluid is passed through a heat exchanger that is exposed to the first fluid. Depending on desired steam requirements, e.g., temperature, pressure, and the like, the source of the first fluid may vary. In some cases, the first fluid is sourced from exhaust gases passing from a gas turbine or from partial combustion of coal or other feedstocks in a gasifier in gasification process. Exhaust gas resulting from the gasification process is referred to as syngas. Syngas, produced in reducing partial combustion process, contains several forms of sulfides i.e. H₂S and chlorides (i.e. HCL). Both sulfides and chlorides are corrosive substances that drive material selection for the heat exchanger. Material selection may also include considerations including cost, service life, and maintenance requirements.

BRIEF DESCRIPTION OF THE DISCLOSURE

According to one aspect of an exemplary embodiment, a modular heat exchanger assembly for a steam generator includes a first fluid inlet conduit configured and disposed to be connected to a source of a first fluid, and a tube sheet coupled to the first fluid inlet conduit. The tube sheet includes a first surface and an opposing, second surface. A plurality of platen tubes extends from the second surface of the tube sheet. The plurality of platen tubes is configured and disposed to carry a second fluid in a heat exchange relationship with the first fluid in a heat exchange vessel. The modular heat exchanger assembly is configured and disposed to be selectively and readily removable from the heat exchange vessel.

According to another aspect of an exemplary embodiment, a heat exchange system includes a gasifier, and a heat exchange vessel coupled to the gasifier. The heat exchange vessel includes an outer surface and an inner surface defining a heat exchange zone. The heat exchange vessel includes an exposed end portion exposing the heat exchange zone. A support ring is arranged on the inner surface adjacent the exposed end portion. A modular heat exchanger assembly is selectively removable arranged in the heat exchange zone. The modular heat exchanger assembly includes a first fluid inlet conduit configured and disposed to be connected to a source of a first fluid. The first fluid inlet conduit is fluidically connected to the heat exchange zone. A tube sheet is supported by the support ring and coupled to the first fluid inlet conduit. The tube sheet includes a first surface and an opposing, second surface. A plurality of platen tubes extends from the second surface of the tube sheet into the heat exchange zone. The plurality of platen tubes is configured and disposed to carry a second fluid in a heat exchange relationship with the first fluid in the heat exchange vessel.

These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings.

BRIEF DESCRIPTION OF DRAWINGS

The subject matter, which is regarded as the invention, is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which:

FIG. 1 depicts a partial view of a gasifier mounted to a heat exchanger having a modular heat exchanger assembly, in accordance with an exemplary embodiment;

FIG. 2 depicts a partial cross-sectional side view of the heat exchanger and modular heat exchanger assembly of FIG. 1;

FIG. 3 depicts a partial end view of a plurality of platen tubes of the modular heat exchanger assembly, in accordance with an aspect of an exemplary embodiment;

FIG. 4 depicts a partial end view of a plurality of platen tubes of the modular heat exchanger assembly, in accordance with another aspect of an exemplary embodiment;

FIG. 5 depicts a partial end view of a plurality of platen tubes of the modular heat exchanger assembly, in accordance with still another aspect of an exemplary embodiment;

FIG. 6 depicts a partial cross-sectional side view of a modular heat exchanger assembly, in accordance with another aspect of an exemplary embodiment;

FIG. 7 depicts a partial cross-sectional side view of a modular heat exchanger assembly, in accordance with yet another aspect of an exemplary embodiment;

FIG. 8 depicts a partial cross-sectional side view of a modular heat exchanger assembly, in accordance with still another aspect of an exemplary embodiment; and

FIG. 9 depicts a partial cross-sectional side view of a modular heat exchanger assembly, in accordance with still yet another aspect of an exemplary embodiment.

The detailed description explains embodiments of the invention, together with advantages and features, by way of example with reference to the drawings.

DETAILED DESCRIPTION OF THE DISCLOSURE

A heat exchanger system, in accordance with an exemplary embodiment, is indicated generally at 2, in FIG. 1. Heat exchanger system 2 includes a gasifier 4 coupled to a heat exchange vessel 6 having a modular heat exchanger assembly 8. Gasifier 4 is supported on a rail 10 through a plurality of wheels 12. In this manner, gasifier 4 may be selectively decoupled from heat exchange vessel 6 to allow for repair and/or replacement of modular heat exchanger assembly 8. Heat exchange vessel 6 includes an outer surface 17 and an inner surface 18 that defines an interior portion 20 receptive of modular heat exchanger assembly 8.

Heat exchange vessel 6 also includes an exposed end portion 22 having a peripheral flange 23. Heat exchange vessel 6 is further shown to include a support ring 26 supported on inner surface 18 and arranged adjacent to exposed end portion 22 and may also include a guide ring 28 (FIG. 2) supported on inner surface 18 spaced from support ring 26. Guide ring 28 may be formed from a number of guide ring segments (not separately labeled) that allow gas in interior portion 20 to pass. An end cover 30 is coupled to exposed end portion 22. End cover 30 includes a peripheral flange member 31 that is joined to peripheral flange 23 through a number of mechanical fasteners (not separately labeled). End cover 30 also includes an inlet 33 having an inlet flange 34 coupled to gasifier 4. Inlet 33 is receptive of syngas as will be detailed below. End cover 30 may also define an outlet zone 36.

As best shown in FIG. 2, modular heat exchanger assembly 8 includes a tube sheet 40 supported by support ring 26. In accordance with an aspect of an exemplary embodiment, support ring 26 extends continuously about inner surface 18. Tube sheet 40 includes a first surface 42 and an opposing second surface 43. A refractory system 44 extends outwardly of first surface 42. Refractory system 44 includes a first or throat portion 45 that extends along inlet 33 and a second or tube sheet refractory portion 46 that extends along second surface 43 of tube sheet 40. Refractory system 44 reduces heat transfer from syngas passing into outlet zone 36.

Modular heat exchanger assembly 8 includes a plurality of tubes or platens 54 extending outwardly of second surface 43 of tube sheet 40. Each of the plurality of platen tubes 54 includes a first end portion 56, a second end portion 57 and an intermediate portion 58. First end portion 56 is coupled to tube sheet 40 and fluidically exposed to outlet zone 36 and second end portion 57 is fluidically coupled to a platen header 60. Platen header 60 is fluidically connected to a source of a second fluid, such as water, through a second fluid inlet header 62. Second fluid inlet header 62 is coupled to platen header 60 through an inlet conduit 63.

Modular heat exchanger assembly 8 also includes a plurality of outer tubes 70 that define a membrane cage 72 which circumscribes the plurality of platen tubes 54 defining a heat exchange zone 73. Each of the plurality of outer tubes 70 includes a first end section 74 and a second end section 75. First end section 74 is fluidically connected to outlet zone 36 and second end section 75 is fluidically connected to a membrane cage header 78. As shown, membrane cage header 78 is fluidically connected to second fluid inlet header 62.

Heat exchange vessel 6 is also shown to include a seal gas inlet 80 that introduces a seal gas into a seal gas zone 81 defined between inner surface 18 and membrane cage 72. Seal gas zone 81 extends between support ring 26 and guide ring 28. Seal gases may be guided between adjacent guide ring segments (not separately labeled) and passed from heat exchange vessel 6 via a nozzle (not shown). Heat exchange vessel 6 is further shown to include a refractory protected membrane cage 84 extending about throat portion 44 of refractory system 44. Refractory protected membrane cage 84 includes an inlet 87 and an outlet 86. A third fluid, which may take the form of water or steam, is introduced into inlet 87 and passed over throat portion 45. In this manner, refractory protected membrane cage 84 provides a thermal barrier between the first fluid passing into interior portion 20 and the second fluid passing into outlet zone 36 while also cooling throat portion 45. At this point, it should be understood that while shown as terminating at first surface 42, platen tubes 54 may extend further into outlet zone 36. For example, platen tubes 54 may extend beyond inlet 87 of refractory protected membrane cage 84.

In accordance with an exemplary aspect, heated first fluid is passed through first or throat portion 45 into interior portion 20. A second fluid is passed into platen header 60 and cage header 78 and flows through plurality of platen tubes 54 and plurality of cage outer 70. The second fluid passes in a heat exchange relationship with the first fluid in interior portion 20. Once heated, the second fluid, typically in the form of steam or steam and/or water, flows through a second fluid outlet 88 extending through end cover 30 and may be passed to a desired destination.

In accordance with an aspect of an exemplary embodiment, plurality of platen tubes 54 is arranged in a substantially linear configuration, such as shown in FIG. 3. More specifically, plurality of platen tubes 54 is arranged in rows (not separately labeled) that extend from membrane cage 72 radially inwardly along a substantially linear path. FIG. 4 depicts an alternate arrangement of the plurality of platen tubes 54. In FIG. 4, plurality of platen tubes 54 is arranged in an L-shaped configuration. In FIG. 5, plurality of platen tubes 54 are shown in a generally triangular arrangement. At this point, it should be understood that plurality of platen tubes 54 may be arranged in a variety of configurations.

Reference will now follow to FIG. 6, wherein like reference numbers represent corresponding parts in the respective views. In accordance with an aspect of an exemplary embodiment, heat exchange vessel 6 includes a support ring 92 formed from a plurality of support ring segments (not separately labeled). Heat exchange vessel 6 is also shown to include a dome member 94 coupled to an outer diameter 95 of tube sheet 40 through a leak tight joint (not shown) which may take the form of a flange joint. Dome member 94 may be coupled with refractory protected membrane cage 84 through a leak tight thermal expansion joint (also not shown). Dome member 94 includes an outer surface 96 and an inner surface 97 that defines an outlet zone 100. An outlet header 104 is fluidically connected to dome member 94, and thus the outlet zone 100. Outlet header 104 delivers steam and/or a mixture of steam and water to an outlet 105. Further shown in FIG. 6, end cover 30 includes a seal gas inlet 107 that delivers a seal gas to the seal gas zone 81 through support ring 26. More specifically, in the exemplary embodiment shown, seal gas is introduced into a space 108 defined between an inner surface (not separately labeled) of end cover 30 and an outer surface 96 of dome member 94. The seal gas may flow between adjacent seal ring segments into seal gas zone 81. At this point, it should be understood that while shown as terminating at first surface 42, platen tubes 54 may extend further into outlet zone 100.

Reference will now follow to FIG. 7, wherein like reference numbers represent corresponding parts in the respective views. In accordance with the exemplary embodiment shown, modular heat exchanger assembly 8 includes a first plurality of platen tubes 116 fluidically coupled to corresponding ones of a second plurality of platen tubes 114 through a connection member 118. In accordance with an aspect of an exemplary embodiment, connection member 118 takes the form of a U-shaped connecting conduit 120. As further shown, an inlet 123 passes through end cover 30 to an inlet header 124. Inlet header 124 is fluidically coupled to each of the first plurality of platen tubes 116. An outlet 128 passes through end cover 30 to an outlet header 129 fluidically connected to each of the second plurality of platen tubes 114.

As still further shown, a throat membrane wall 134 includes an inlet 135 fluidically coupled to inlet header 124 and an outlet 136 fluidically coupled to outlet header 129. In a manner similar to that discussed above, throat membrane wall 134 provides a thermal shield to refractory system 44 as well as provides a leak tight pressure boundary for the inlet 33. In accordance with the exemplary aspect shown, the second fluid may be introduced into inlet header 124, passed through platens 116 and 114 in a heat exchange relationship with the first fluid, in interior portion 20 producing a heated second fluid. The heated second fluid is passed from outlet header 129 to a desired destination.

FIG. 8, wherein like reference numbers represent corresponding parts in the respective views, depicts a steam separator 142 fluidically connected to outlet header 129. Steam separator 142 separates water entrained in the steam and includes a steam outlet 144 and a saturated steam outlet 146 fluidically connected to outlet zone 36. A superheated steam outlet 148 also extends from end cover 30. FIG. 9, depicts steam separator 142 fluidically coupled to outlet zone 100 of dome member 94.

At this point it should be understood that the exemplary embodiment describes a heat exchanger configured to create steam by exposing water to a high temperature stream that may be syngas generated through a gasification process of coal, natural gas, biomass, heavy oil or several other fuels. The syngas may be at a temperature of about 2,500° F. (1,370° C.) and at pressures of about 300 psig (2060 kpa) or more to produce a high pressure steam, or steam having a pressure of about 1500 psig (10,340 kpa) or more. Further it should be understood that the modular heat exchanger assembly may be readily removed and or replaced. More specifically, syngas includes various corrosives that may damage heat exchanger components. By forming the heat exchanger components as a module, replacement and or repair may be effected without leading to undesirable downtimes. Further, the use of a module enables repair and/or replacement in areas that are otherwise inaccessible to devices needed to move an entire heat exchanger.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one more other features, integers, steps, operations, element components, and/or groups thereof.

The term “about” is intended to include the degree of error associated with measurement of the particular quantity based upon the equipment available at the time of filing the application. For example, “about” can include a range of ±8% or 5%, or 2% of a given value.

While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims. 

What is claimed is:
 1. A modular heat exchanger assembly for a steam generator comprising: a first fluid inlet conduit configured and disposed to be connected to a source of a first fluid; a tube sheet coupled to the first fluid inlet conduit, the tube sheet including a first surface and an opposing, second surface; and a plurality of platen tubes extending from the second surface of the tube sheet, the plurality of platen tubes being configured and disposed to carry a second fluid in a heat exchange relationship with the first fluid in a heat exchange vessel, the modular heat exchanger assembly being configured and disposed to be selectively and readily removable from the heat exchange vessel.
 2. The modular heat exchanger assembly according to claim 1, wherein each of the plurality of platen tubes includes a first end portion, a second end portion and an intermediate portion defining a conduit extending therebetween, the first end portion being exposed at the first surface of the tube sheet.
 3. The modular heat exchanger assembly according to claim 2, further comprising: a platen header provided at the second end portion of the plurality of platen tubes, the platen header fluidically connecting each of the plurality of platen tubes at the second end portion.
 4. The modular heat exchanger assembly according to claim 3, further comprising: a second fluid inlet conduit fluidically connected to the platen header.
 5. The modular heat exchanger assembly according to claim 2, further comprising: a dome member arranged at the first surface of the tube sheet, the dome member fluidically connecting the first end portion of each of the plurality of platen tubes.
 6. The modular heat exchanger assembly according to claim 5, further comprising: an outlet fluidically connected to the dome member.
 7. The modular heat exchanger assembly according to claim 2, wherein the second end portion of select ones of the plurality of platen tubes is fluidically connected to the second end portion of select ones of others of the plurality of platen tubes.
 8. The modular heat exchanger assembly according to claim 1, further comprising: a plurality of outer tubes defining a membrane cage surrounding the plurality of platen tubes.
 9. The modular heat exchanger assembly according to claim 8, further comprising: an inlet conduit fluidically connected to the plurality of outer tubes defining the membrane cage.
 10. The modular heat exchanger assembly according to claim 1, wherein the plurality of platen tubes is arranged in one of a substantially linear configuration, an L-shaped configuration, and a triangular pitch configuration.
 11. A heat exchanger system comprising: a gasifier; a heat exchange vessel coupled to the gasifier, the heat exchange vessel including an outer surface and an inner surface defining a heat exchange zone, the heat exchange vessel including an exposed end portion exposing the heat exchange zone; a support ring arranged on the inner surface adjacent the exposed end portion; and a modular heat exchanger assembly selectively removably arranged in the heat exchange zone, the modular heat exchanger assembly comprising: a first fluid inlet conduit configured and disposed to be connected to a source of a first fluid, the first fluid inlet conduit being fluidically connected to the heat exchange zone; a tube sheet supported by the support ring and coupled to the first fluid inlet conduit, the tube sheet including a first surface and an opposing, second surface; and a plurality of platen tubes extending from the second surface of the tube sheet into the heat exchange zone, the plurality of platen tubes being configured and disposed to carry a second fluid in a heat exchange relationship with the first fluid in the heat exchange vessel.
 12. The heat exchanger system according to claim 11, wherein each of the plurality of platen tubes includes a first end portion, a second end portion and an intermediate portion defining a conduit extending therebetween, the first end portion being exposed at the first surface of the tube sheet.
 13. The heat exchanger system according to claim 12, further comprising: a platen header provided at the second end portion of the plurality of platen tubes, the platen header fluidically connecting each of the plurality of platen tubes at the second end portion.
 14. The heat exchanger system according to claim 13, further comprising: a second fluid inlet conduit extending through the outer surface and fluidically connected to the platen header.
 15. The heat exchanger system according to claim 12, further comprising: a dome member arranged at the first surface of the tube sheet, the dome member fluidically connecting the first end portion of each of the plurality of platen tubes.
 16. The heat exchanger system according to claim 15, further comprising: an outlet zone fluidically connected to the dome member.
 17. The heat exchanger system according to claim 11, further comprising: an end cover coupled to the exposed end portion of the heat exchange vessel, the first fluid inlet conduit extending through the end cover.
 18. The heat exchanger system according to claim 17, further comprising: a refractory cage extending through the end cover along the first fluid inlet conduit, the refractory cage thermally isolating the first fluid inlet conduit from the second fluid in the heat exchange zone.
 19. The heat exchanger system according to claim 11, further comprising: a plurality of outer tubes defining a membrane cage surrounding the plurality of platen tubes; and an inlet conduit fluidically connected to the plurality of outer tubes defining the membrane cage.
 20. The heat exchanger system according to claim 11, wherein the plurality of platen tubes is arranged in one of a substantially linear configuration, an L-shaped configuration, and a triangular pitch configuration. 